I tried importing old custom levels. But many of them have problems with launching or at the very end:
1. The graphical interface (number of lives, timer) is not displayed.
2. At the end of the level, the game simply freezes.
3. When importing some levels, an error message appears: "The color value cannot be greater than 255".
It is also not very convenient to manually create a file with a list of levels. Especially if errors occur during import (for example, the above problem with incorrect recognition of the level structure).